A conventional combustible gas turbine engine includes a compressor section, a combustion section including a plurality of combustor apparatuses, and a turbine section. Ambient air is compressed in the compressor section and directed to the combustor apparatuses in the combustion section. The pressurized air is mixed with fuel and ignited in the combustor apparatuses to create combustion products that define working gases. The working gases are routed to the turbine section via a plurality of transition ducts. Within the turbine section are rows of stationary vanes and rotating blades. The rotating blades are coupled to a shaft and disc assembly. As the working gases expand through the turbine section, the working gases cause the blades, and therefore the shaft, to rotate.
It is known that injecting fuel at two axially spaced apart fuel injection locations, i.e., via an upstream fuel injection system associated with a main combustion zone and a downstream fuel injection system downstream from the main combustion zone, reduces the production of NOx by a combustor apparatus. For example, if a significant portion of fuel is injected at a location downstream of the main combustion zone, i.e., by the downstream fuel injection system, the amount of time that second combustion products, created by the fuel injected by the downstream fuel injection system, are at a high temperature is reduced as compared to first combustion products, created by the fuel injected into the main combustion zone by the upstream fuel injection system. Since NOx production is increased by the elapsed time that combustion products are at a high combustion temperature, combusting a portion of the fuel downstream of the main combustion zone reduces the time the second combustion products are at a high temperature, such that the amount of NOx produced by the combustor apparatus is reduced.